In the building-construction or architectural field, solar energy systems are typically categorized as either passive systems or active systems. In conventional passive solar energy systems the architectural design, the natural materials and/or absorptive structures of the building are used as an energy-saving system. The building itself is used as a solar collector and storage device. An example would be thick-walled stone and adobe dwellings that slowly collect heat during the day and gradually release it at night. Passive systems require little or no investment of equipment external to the building's own structure. Conventional active solar energy systems typically require a separate solar collector, a separate storage device, and then pumps, fans etc. that draw heat from storage when it is available. Some systems are fluid-mechanical system, such as an insulated fluid-holding tank into or through which is pumped a heat-absorbing fluid medium (such as air, water, or an antifreeze solution), which fluid is circulated to distribute the collected heat energy. The size of an adequate fluid-holding tank and volume of fluid required to be in the system depends partly on the size of the building and partly on the typical number of sunless days during the heating season.
A passive solar-energy system cannot be readily installed on conventionally-constructed buildings--generally major modifications of the architectural design, the materials and/or structures of the building would be required. The installation of an active solar-energy system on conventionally-constructed buildings is also a problem, requiring not only the installation of a fluid circulation system, but also the tank, controls, fans, pumps and the like required for the collector and storage facilities. In addition, an active system often requires at least some of the equipment to be sited external to the building structure.
It is an object of the present invention to provide a solar-energy system with which an existing, conventionally-constructed building can be readily retrofitted, and which can easily be installed during building construction without incurring excessive construction costs, and which does not equipment sited external to the building structure. It is an object of the present invention to provide such a solar-energy system which is also the primary thermal insulator of the building walls, and which also both converts solar energy into heat in cold weather, such as during winter, and prevents the building from overheating during warm weather, such as during summer.